The National Institutes of Health (NIH) has identified the prospective investigation of osteoporosis in gender, age, and racially/ethnically diverse populations as an urgent research priority (Consensus Development Conference on Osteoporosis Prevention, Diagnosis, and Therapy. 2000). Male osteoporosis is a highly prevalent medical condition, with enormous impact on the health, medical-care expenditures, and quality of life of the aging U.S. male population. Race/ethnic-specific estimates of the prevalence of osteoporosis from population based. cross-sectional data are limited by: (1) Incomplete information on the range of variables that may be related to both bone density and race/ethnicity (e.g., bone turnover, hormone levels, lifestyle, nutrition, vitamin D status, and others) that might account for the racial/ethnic difference in prevalence; and (2) Limited data on Hispanics other than Mexican Americans, despite the well-known heterogeneity of ethnicities within Hispanic populations. The New England Research Institutes (NERI) has received an award from NIDDK to begin a large epidemiological research study of 3,000 randomly selected, community dwelling Hispanic, non-Hispanic African American, and non-Hispanic Caucasian men ages 40-79 years (1,000 per racial/ethnic group), to provide normative data on four urologic conditions. The proposed study will take advantage of this newly assembled cohort by adding a cross-sectional, population-based sub-study of bone density and osteoporosis in men. We will recruit 900 men from the parent study and describe the distribution of bone mineral density (BMD) and low BMD by race/ethnicity and determine to what extent variables (e.g., health status, lifestyle, sociodemographics, biochemical measures of bone turnover and hormone levels, fracture history) correlate with BMD, and whether the effect of these variables on BMD varies with race/ethnicity. To prepare for the possibility of a future, separately funded prospective study, we will initiate panel maintenance activities with the cohort. This design represents a cost-efficient approach to gathering detailed information focused on bone health in a randomly selected, population-based sample, while taking advantage of the activities currently underway as part of the parent study.